This article discusses the pressing and sintering of various refractory metal powders for the production of intermediate products as well as special cases of finished products. The metal powders considered include tungsten, molybdenum, tantalum, niobium and their alloys, as well as rhenium.

Blending of powders is defined as the thorough intermingling of powders of the same nominal composition. Premixing is the preparation of a uniform mixture of two or more components. This article provides information on the blending and premixing variables required to produce adequate results in the powder mixture. It describes the effects of metal powder characteristics on blending and mixing: particle size, shape, density, and surface features. The article also provides information on the equipment, tumble-type blenders, and low-shear agitated-type blenders used for blending and premixing solids.

Refractory metals are typically processed from powders into ingots that are subsequently swaged into round bars or rolled into plates. Secondary operations are required to fabricate more complex refractory metal components. This article discusses two such secondary operations, namely, machining and joining processes for tungsten, tungsten heavy alloys, molybdenum, tantalum, niobium, and rhenium components. It describes the various types of metal joining processes, including mechanical fastening, brazing, and welding.

Metal powders are used as fuels in solid propellants, fillers in various materials, such as polymers or other binder systems, and for material substitution. They are also used in food enrichment, environmental remediation market, and magnetic, electrical, and medical application areas. This article reviews some of the diverse and emerging applications of ferrous and nonferrous powders. It also discusses the functions of copier powders and the processes used frequently for copier powder coating.

The residual porosity in sintered refractory metal ingots is usually eliminated by different densification processes, such as thermomechanical processes. This article focuses on thermomechanical processing of tungsten, molybdenum, and tantalum. It provides an overview of liquid-phase sintering of tungsten heavy alloys and describes the infiltration of tungsten and molybdenum for attaining full density. The article concludes by providing information on hot isostatic pressing of refractory metal alloys to full density.

The primary market for metal powder is the production of powder metallurgy (PM) parts, which are dominated primarily by iron and copper powders. This article reviews the chemical and pyrotechnics applications of ferrous and nonferrous powders. It describes the characteristics of iron powder used in oxygen scavengers and chemical reactive warmers and heaters. Metal powders used as fuels in solid propellants, pyrotechnic devices, explosives, and similar applications are reviewed. Atomized aluminum, magnesium, tungsten, and zirconium powders are also discussed.

This article describes several factors, which help in determining the compressibility of metal powders: particle shape, density, composition, hardness, particle size, lubrication, and compacting. It discusses the uses of annealing metal powders and describes compressibility testing of the powders. The article details green strength and its mechanism and the variables affecting the strength. It also discusses two test methods for determining the green strength: the Rattler test and the transverse bend test.

Refractory metals are extracted from ore concentrates or scrap, processed into intermediate chemicals, and then reduced to metal, usually in powder form. This article discusses the raw materials needed and the processing steps for producing pure and alloyed refractory metal powders. The effects of processing conditions on the physical and chemical properties of tungsten, molybdenum, tantalum, niobium, and rhenium powders are reviewed.

This article focuses on direct extrusion processing where metal powders undergo plastic deformation, usually at an elevated temperature, to produce a densified and elongated form having structural integrity. It provides information on the basic powder extrusion processes and the mechanics of extrusion. The article also examines specific extrusion practices for the production of wrought material from powder stock and provides examples of materials processed by powder extrusion.

During metal powder production, powder and/or dust handling, compaction, and part finishing operations, many safety and environmental risks exist. This article is a detailed account of the types of safety hazards that can exist and the issues that occur during metal powder handling, as well as recommendations and strategies that can be employed to both prevent and protect against damaging effects from powder exposure, fire and/or explosions, or environmental impact events.